The present invention relates in general terms to motor vehicle headlights equipped with a discharge lamp.
Discharge lamps, especially of the metal halide type (typically sodium iodide) are more and more frequently used as light sources in such headlights.
In this connection they display the appreciable advantage that, for a comparable power consumption, they are able to provide a much greater light intensity than in the case of conventional halogen filament lamps.
However, these lamps do have the disadvantage that in their arc they give rise to electromagnetic fields which pose a serious problem in regard to the requirements for electromagnetic compatibility, as to both emission and reception, which are generally imposed by regulations. In this connection it will be observed that these requirements are today becoming more and more severe through the development of electronic circuits which provide certain security functions on board a vehicle.
While there do indeed exist arrangements for screening as much as possible a discharge lamp and its power supply circuits, such arrangements are generally incompatible with the specific environment of a motor vehicle headlight. Thus for example, it is impossible to place the whole of the headlight within a Faraday cage by which it is completely surrounded, because it is necessary to leave free the region for exit of light in the, region of the cover glass.
The present invention aims to overcome these limitations in the state of the art, and to propose a motor vehicle headlight which has a discharge lamp and improved screening means, in particular for the arc of the lamp, which are simple to construct and apply.
Another object of the invention is to ensure, without any particular intervention, electrical continuity between a screen of a high tension connector for a discharge lamp and other screening components of the headlight, once the connector has been fitted in place.
To this end, the invention proposes a motor vehicle headlight, comprising a reflector on which there is fixed a lamp holder for holding a discharge lamp, and a high tension connector adapted to be engaged on the lamp which is mounted in the lamp holder to provide electrical power to the said lamp, characterised in that the reflector has an electrically conductive layer, in that the lamp holder has a metallic portion fixed on the reflector in such a way as to be in electrical contact with the said layer, in that the connector has a metallic screening envelope, and in that the said portion of the lamp holder and/or the connector has at least one elastically deformable conductive tongue for providing electrical continuity between the said portion of the lamp holder and the connector during fitting of the said connector.
Aspects, which are preferred but not limiting, of the headlight in accordance with the invention are as follows:
A plurality of resilient tongues are provided.
The or each resilient tongue is part of the lamp holder.
The or each resilient tongue is formed integrally with the said portion of the lamp holder.
The or each resilient tongue has, in its free end region, a profile which defines a portion projecting towards the connector and the lamp holder respectively.
The said profile is a V-shaped profile.
The or each resilient tongue extends substantially parallel to the direction of fitting of the connector.
The or each resilient tongue extends substantially radially inwards from a crown which is part of the lamp holder, and within which the said high tension connector is adapted to be engaged.
The said conductive layer of the reflector is applied on a back face of the reflector, and with electrical continuity on a surface of the reflector adapted for mounting of the said crown thereon.
The said conductive layer of the reflector consists of the reflector itself, which is formed from metallic plate.